16-Nights Galapagos Wildlife Photo Expedition from $19,995

Also known as San Salvador or James, Santiago is the fifth-largest and one of the most visited of the Galapagos Islands. It is uninhabited, and there was a failed attempt at colonizing it in the 1930s. There are three visitor sites, and the two on the western coast of the island are Puerto Egas and Playa Espumilla.

Puerto Egas, on James Bay, offers a black-sand landing beach with impressive wind-carved, tuff-stone layers. The relatively flat, black-lava shoreline is broken up by pools, caves and promenades, where hundreds of marine iguanas sun themselves, seek mates and slither into the sea. Their black skin camouflages them among the lava rocks.

Playa Espumilla is a nesting area for sea turtles and, when the lagoon is filled, a place to see white-cheeked pintail ducks and flamingos. The estimated flamingo population on the Galapagos is around 500-1,000. These animals are an endemic subspecies of the flamingos commonly found in the Caribbean region.

Dozens of bright red-orange Sally Lightfoot crabs, among the only people-shy creatures on the islands, frolic in the tide pools and scurry on the rocks. The area also has a colony of fur seals, which are endemic to the islands but closely related to fur seals in Antarctica. The snorkeling is good along the rocks, where it's possible to see colorful fish, moray eels and sharks.

At the east end of the island is Sullivan's Bay (across from Bartolome Island). A volcano spewed a stream of lava there in 1897, and it still reaches to the sea. Visitors can follow a marked trail over the lava to see fascinating untouched volcanic formations such as pahoehoe lava. Only a few plants have taken hold there, including an unusually shaped cactus and some carpetweed.

Sombrero Chino (Chinese Hat) is a popular snorkeling spot 656 ft/200 m off the coast. These beautiful waters are a playground for sea lions, sharks, penguins and manta rays. A series of seven diving sites offer divers the chance to get up close to the best of Galapagos' marine life.

The largest of the islands, Isabela has the Galapagos' tallest peak—Volcano Wolf—at 5,487 ft/1,646 m. The island resembles a sea horse when seen on a map. Also known as Albemarle, the island was formed when six volcanoes erupted and melded together. About 2,000 people reside there, mostly on the southern tip of the island in Puerto Villamil. Few cruise ships visit the town, but they do stop regularly at several park sites elsewhere on the island.

Tagus Cove on the western side, across from Fernandina Island, was a favorite spot of pirates and whalers, who scrawled the names of their ships on the surrounding cliffs. Visitors can hike from the bay up a steep hill to Darwin's Lake, the cone of an old volcano that's full of green sulfur and saltwater. Those who continue partway up the base of Volcano Darwin can take in panoramic views of nearby islands. Galapagos penguins and the world's only flightless cormorants are often visible along the shore. Three types of finches that Darwin collected on his visit to Isabela are also present.

Other sites on the west coast that are often visited by cruise ships include Urvina Bay, with giant tortoises, iguanas, flightless cormorants and pelicans; Elizabeth Bay, an aquatic mangrove forest that pangas sometimes explore (with motors off) in search of green turtles, rays and sea birds that inhabit its lagoons and channels; and Punta Moreno, which offers the chance to see a variety of birds, including great blue herons and flamingos.

To see the island's other sites, longer stays are required. Overnight visitors staying at Puerto Villamil can take a bus to the base of Volcano Sierra Negra and then walk or ride horses to its rim for wonderful views. Volcano Alcedo, in the center of the island, used to be the centerpiece of a four-hour hike, but a massive campaign to eradicate feral goats has put a moratorium on this excursion.

The town of Puerto Villamil has a pleasant beach, with a dozen or more cafes, shops and hotels located right on the beach. Nearby is Lover's Beach, a good place to view sea birds. Las Tintoreras is a great location to watch resting whitetip reef sharks, large marine iguanas, rays and Galapagos penguins.